Process for the production of a composite polymer material with increased filler content

ABSTRACT

An inventive process for the production of a composite polymer material is provided allowing for the preparation of a composite polymer material with high filler content which may be used as a masterbatch.

The present invention relates to a process for the production of acomposite polymer material with increased filler content and to the useof said composite polymer material.

Increasing costs for the production of polymers are driving developmentof methods for the provision of higher levels of fillers in compositepolymer materials. Said fillers are frequently selected from natural orsynthetic minerals such as calcium carbonate, chalk, limestone, marble,dolomite, titanium dioxide, barium sulphate, talc, clay, or mica.

In a conventional process for the production of a composite polymermaterial a polymer material and a filler material may be mixed in ahot-cold mixer to form a polymer dry-blend. The polymer dry-blend thenis usually conveyed pneumatically to a compounder, typically anextruder, in which the composite polymer material is formed.

Composite polymer materials with increased filler content and methodsfor the production of the said composite polymer materials are knownfrom the prior art.

EP 1 584 650 A1 discloses a masterbatch pellet comprising athermoplastic resin and 2 to 60% by weight of a white combustioncatalyst blended in the thermoplastic resin. The masterbatch pellets aresuitable for producing a thermoplastic resin composition exhibiting acombustion-promoting effect.

IE 930545 discloses the use of a masterbatch material which may be addedto a recycle line of oversize material of an extruding device.

EP 1 421 136 B1 discloses a method for the production of a masterbatchcarrier, which method includes blending of at least one chlorinatedpolyolefin, at least one acrylic processing aid, at least one acrylicimpact modifier and forming the blend into a shaped body. In particular,the method is directed towards a method for the provision of amasterbatch suitable for use in colouring of polyvinyl chloride. Saidmasterbatch may further include a filler.

US 2003/0144423 A1 is directed to polyvinyl chloride compositions havingimproved impact strength. The composition may comprise a vinyl chloridepolymer, at least one ethylene/alpha-olefin copolymer and at least onerandomly chlorinated olefin polymer. Optionally, the compositions mayhave inorganic filler levels from 5 to 50 phr.

WO 2010/049530 A2 relates to profiles made from foamed polyvinylchloride comprising at least 40 phr, preferably at least 60 phr ofnaturally occurring mineral filler, and polyvinyl chloride with ak-value of 50 to 58. The filler preferably is talc and/or mica and morepreferably is talc. The document further discloses a method according towhich two steps, a first and a second mixing step, are used in order toreduce problems like segregation and quality loss. Major part of thefiller is added in said second mixing step which is carried out at atemperature higher than 180° C.

According to H. Müller in Kunststoffe International 12/2006, 62-66, acalcium carbonate containing polyvinyl chloride is disclosed, whereinsaid calcium carbonate is added to a polyvinyl chloride dry-blenddirectly prior to an extruder by means of direct addition technology.According to said method 5 to 50 phr calcium carbonate may be added.

However, conventional methods known in the art for the production ofcomposite polymer materials have several disadvantages when applied inthe production of composite polymer materials with increased fillercontent. Typically, problems in conventional methods for the productionof composite polymer materials begin to arise at filler contents above20 to 30 phr.

For example, addition of increased amounts of filler material, i.e.amounts above 20 to 30 phr, to a polymer when applying conventionalmethods leads to increased mixing times.

Another disadvantage when applying conventional methods in theproduction of composite polymer materials with increased filler contentis the formation of filler material deposits on the walls of thehot-cold mixer.

Yet another disadvantage when applying conventional methods in theproduction of composite polymer materials with increased filler contentis the segregation of polymer material and filler material in thedry-blend when pneumatically conveying the dry-blend obtained from thehot-cold mixing to the compounder. This in turn results in non-uniformfiller contents of the produced composite polymer material.

In view of the foregoing, improving the process for the provision ofcomposite polymer materials with increased filler content remains ofinterest for the skilled person.

It is therefore an object to provide a process according to which costlyand energy-intensive mixing times may be reduced. The consumption ofelectrical energy, e.g. during the hot-cold mixing, may be reduced dueto the fact that the mineral filler material introduced via directaddition technology does not necessarily require a heating step and asubsequent cooling step.

It is a further object to provide a process according to which theformation of filler material deposits in the hot-cold mixer may beavoided.

It is a further object to provide a process according to whichsegregation problems when pneumatically conveying the dry-blend obtainedfrom the hot-cold mixer to the compounder may be avoided.

It is yet a further object to provide a composite polymer material withincreased filler content which may be incorporated into polymer productsand thereby increasing the filler content of said polymer product.

It would also be desirable to provide a composite polymer material thatallows adapting the filler content of a polymer product to apredetermined value and moreover may be dosed precisely and uniformly.

The foregoing and other objects are solved by the subject-matter asdefined herein in the independent claims.

According to one aspect of the present invention a process for theproduction of a composite polymer material is provided, comprising thesteps of:

-   -   (a) providing a mineral filler material;    -   (b) providing a polymer material;    -   (c) conveying the mineral filler material of step (a) and the        polymer material of step (b) to a compounder;    -   (d) forming a composite polymer material in said compounder;        wherein the mineral filler material of step (a) is added to the        polymer material of step (b) in an amount so that the mineral        filler content of the resulting composite polymer material is in        the range from 60 to 900 phr and wherein said addition is        performed by use of direct addition technology.

According to another aspect the present invention relates to theprovision of a composite polymer material obtainable by the inventiveprocess.

According to yet another aspect of the present invention, a compositepolymer material is provided comprising a mineral filler material and apolymer material, wherein the composite polymer material is in the formof grains having an average grain size of less than 4 mm, preferablyless than 3 mm and most preferably less than 2 mm, and wherein thefiller content in the composite polymer material is in the range from 60to 900 phr.

According to yet another aspect of the present invention a polymerproduct comprising the inventive composite polymer material is provided.

Another aspect of the present invention relates to the use of theinventive composite polymer material in polymer products wherein thecomposite material is preferably used as a masterbatch.

Advantageous embodiments of the inventive process are defined in thecorresponding subclaims.

According to one embodiment of the inventive process the mineral fillercontent of the resulting composite polymer material is in the range from150 to 800 phr, preferably in the range from 160 to 700 phr and morepreferably in the range from 170 to 600 phr.

According to another embodiment of the inventive process the compositepolymer material in step (d) is produced in form of a granulate havingan average grain size ranging from 2 to 8 mm, preferably from 3 to 7 mmand more preferably from 4 to 6 mm.

According to still another embodiment of the inventive process theobtained composite polymer material is micronized to yield an averagegrain size of less than 4 mm, preferably less than 3 mm and mostpreferably less than 2 mm.

According to another embodiment of the inventive process the polymermaterial provided in step (b) comprises a mineral filler material,wherein the content of the mineral filler material in the polymermaterial preferably is in the range from 1 to 70 phr, preferably from 5to 60 phr and more preferably from 10 to 50 phr.

According to another embodiment of the inventive process the polymermaterial provided in step (b) comprises a recycled polymer material,wherein the recycled polymer material preferably comprises a micronizedrecycled polymer material.

According to another embodiment of the inventive process said compounderis an extruder, wherein the temperature of the polymer melt preferablyis kept below 205° C.

According to another embodiment of the inventive process the mineralfiller material is selected from the group consisting of calciumcarbonate, chalk, limestone, marble, dolomite, titanium dioxide, bariumsulphate, talc, clay, or mica, and mixtures thereof, wherein the mineralfiller material preferably is calcium carbonate and/or dolomite.

According to a preferred embodiment of the inventive process the mineralfiller material is selected from ground dolomite, ground calciumcarbonate (GCC), precipitated calcium carbonate (PCC), modified calciumcarbonate (MCC), or mixtures thereof.

According to still another embodiment of the inventive process thepolymer material comprises a polymer selected from the group consistingof vinyl polymers, vinyl copolymers, acryl polymers, acryl copolymers,chlorinated polyethylenes, and mixtures thereof, wherein the polymermaterial preferably comprises vinyl polymers and/or vinyl copolymers,and more preferably is a polyvinyl chloride.

According to another embodiment of the inventive composite polymermaterial the mineral filler content of the composite polymer material isin the range from 150 to 800 phr, preferably in the range from 160 to700 phr and more preferably in the range from 170 to 600 phr.

According to still another embodiment of the inventive composite polymermaterial the mineral filler material is selected from the groupconsisting of calcium carbonate, chalk, limestone, marble, dolomite,titanium dioxide, barium sulphate, talc, clay, or mica, and mixturesthereof, wherein the mineral filler material preferably is calciumcarbonate and/or dolomite.

According to another embodiment of the inventive composite polymermaterial the polymer material comprises a polymer being selected fromthe group consisting of vinyl polymers, vinyl copolymers, acrylpolymers, acryl copolymers, chlorinated polyethylenes, and mixturesthereof, wherein the polymer material preferably comprises vinylpolymers and/or vinyl copolymers, and more preferably comprises apolyvinyl chloride.

According to another embodiment of the inventive composite polymermaterial the k-value of the polymer material is in the range from 30 to100, preferably from 45 to 70 and most preferably from 50 to 68, whereinthe polymer material preferably is a polyvinyl chloride.

According to a preferred embodiment the polymer product is a granulate,window profile, pipe, technical profile, wall panel, ceiling panel,cladding panel, wire or cable insulation, film, sheet, fibre, or anon-woven.

It should be understood that for the purposes of the present invention,the following terms have the following meanings:

The term “mineral filler material” in the meaning of the presentinvention refers to substances of mineral origin, which may be added tomaterials such as paper, polymers, rubber, paints or adhesives, e.g. tolower the consumption of more expensive materials and/or to enhancetechnical properties of the products. The person skilled in the art verywell knows the typical fillers used in the respective fields.

The term “mineral” as used herein encompasses abiogenic and solidmaterial with an ordered atomic structure.

A “polymer material” as used in this application comprises homopolymers,copolymers such as, for example, block, graft, random and alternatingcopolymers, heterophasic copolymers and random heterophasic copolymersas well as polymer blends, modifications and mixtures thereof. The termpolymer material as used herein may likewise comprise recycled polymermaterials, e.g. recycled polyvinyl chloride. The content of recycledpolymer material in the polymer material may be in the range from 0.1 to100 wt.-%.

A “composite polymer material” as used in this application is a materialcomprising at least one polymer and at least one mineral fillermaterial.

The “compounder” according to the present application may be any devicewhich is suitable for compounding of one or more polymer material withone or more additive, e.g. a mineral filler material. Said compoundercomprises a compounding section, in which the mineral filler materialand the polymer material are actually compounded. Such devices are knownin the art.

The term “direct addition technology” as used herein comprises theaddition and mixing of a mineral filler material to a polymer materialin a direct addition device upstream from a compounding section of acompounder, wherein the direct addition device is in direct connectionto the compounding section of the compounder and preferably above saidcompounding section of the compounder, so that no pneumatic conveying ofthe resulting mixture to the compounding section is involved.

The term “granulate” as used in this application refers to a productobtained by a granulation process. The granulate may have a definedshape such as, for example, pellets, spheres, pearls, beads, prills,flakes, chips or slugs, a non-defined shape such as, for example,crumbles, or it may be a mixture of both defined and non-defined shapecomposite polymer materials. Granulation may be carried out, e.g. with acompounder as defined above, by pressing a polymer melt through a dieequipped with a cutting knife, wherein the granule size may be regulatedby the applied pressure and/or the cutting speed. However, any othersystem that is suitable to produce granulates may be used.

The term “micronization” refers to methods for the size reduction ofgranulates. Such methods for the reduction of the average grain sizeinclude, without being limited to, milling, bashing and grinding as wellas methods involving supercritical fluids. A micronized granulate mayhave an average grain size in the range from 100 to 4000 μm.

The “average grain size” of the composite polymer material is the weightmedian grain size, i.e. 50 wt.-% of all grains are bigger or smallerthan this average grain size. The grain size is determined by sievingaccording to ISO 3310-1:2000 (E).

The unit “phr” (parts per hundred resins) as used herein refers to theparts by dry weight of an ingredient per hundred parts by dry weight ofa reference polymer.

The “k-value” is a measure of the molecular weight of a polymer, e.g. ofa polyvinyl chloride, based on measurements of viscosity of a polymersolution. It ranges usually from 30 to 100. Low k-values imply lowmolecular weight (which is easy to process but has inferior properties)and high k-values imply high molecular weight (which is difficult toprocess, but has outstanding properties).

The term “masterbatch” refers to a polymer composite material which isused in the production of a polymer product. A masterbatch may be added,e.g. prior to extrusion, to a polymer product in order to achieve e.g.higher filler contents when using a mineral filler masterbatch.

“Ground calcium carbonate” (GCC) in the meaning of the present inventionis a calcium carbonate obtained from natural sources, such as limestone,marble, calcite, or chalk, and processed through a wet and/or drytreatment such as grinding, screening and/or fractionation, for exampleby a cyclone or classifier.

“Precipitated calcium carbonate” (PCC) in the meaning of the presentinvention is a synthesized material, generally obtained by precipitationfollowing a reaction of carbon dioxide and calcium hydroxide (hydratedlime) in an aqueous environment or by precipitation of a calcium- and acarbonate source in water. Additionally, precipitated calcium carbonatecan also be the product of introducing calcium and carbonate salts,calcium chloride and sodium carbonate for example, in an aqueousenvironment. PCC may be vaterite, calcite or aragonite. PCCs aredescribed, for example, in EP 2 447 213 A1, EP 2 524 898 A1, EP 2 371766 A1, or unpublished European patent application No. 12 164 041.1.

“Modified calcium carbonate” (MCC) in the meaning of the presentinvention may feature a natural ground or precipitated calcium carbonatewith an internal structure modification or a surface-reaction product,i.e. surface-reacted calcium carbonate.

Throughout the present document, the “particle size” of the fillermaterial is described by its distribution of particle sizes. The valued_(x) represents the diameter relative to which x % by weight of theparticles have diameters less than d_(x). This means that the d₂₀ valueis the particle size at which 20 wt.-% of all particles are smaller, andthe d₉₈ value is the particle size at which 98 wt.-% of all particlesare smaller. The d₉₈ value is also designated as “top cut”. The d₅₀value is thus the weight median particle size, i.e. 50 wt.-% of allparticles are bigger or smaller than this particle size. For the purposeof the present invention the particle size is specified as weight medianparticle size d₅₀ unless indicated otherwise. For determining the weightmedian particle size d₅₀ value or the top cut particle size d₉₈ value aSedigraph 5100 or 5120 device from the company Micromeritics, USA, canbe used.

Where an indefinite or definite article is used when referring to asingular noun, e.g. “a”, “an” or “the”, this includes a plural of thatnoun unless something else is specifically stated.

Where the term “comprising” is used in the present description andclaims, it does not exclude other elements. For the purposes of thepresent invention, the term “consisting of” is considered to be apreferred embodiment of the term “comprising of”. If hereinafter a groupis defined to comprise at least a certain number of embodiments, this isalso to be understood to disclose a group, which preferably consistsonly of these embodiments.

Terms like “obtainable” or “definable” and “obtained” or “defined” areused interchangeably. This e.g. means that, unless the context clearlydictates otherwise, the term “obtained” does not mean to indicate thate.g. an embodiment must be obtained by e.g. the sequence of stepsfollowing the term “obtained” though such a limited understanding isalways included by the terms “obtained” or “defined” as a preferredembodiment.

According to the present invention, the process for the production of acomposite polymer material comprises the steps of:

-   -   (a) providing a mineral filler material;    -   (b) providing a polymer material;    -   (c) conveying the mineral filler material of step (a) and the        polymer material of step (b) to a compounder;    -   (d) forming a composite polymer material in said compounder;        wherein the mineral filler material of step (a) is added to the        polymer material of step (b) in an amount so that the mineral        filler content of the resulting composite polymer material is in        the range from 60 to 900 phr and wherein said addition is        performed by use of direct addition technology.

In the following preferred embodiments of the inventive process for theproduction of a composite polymer material will be set out in moredetail. It is to be understood that these technical details andembodiments also apply to the inventive composite polymer material andthe use of said inventive composite polymer material.

As set out above, the inventive process for the production of acomposite polymer material comprises the steps (a), (b), (c) and (d). Inthe following, it is referred to further details of the presentinvention and in particular to the foregoing steps of the inventiveprocess.

Characterization of Step (a):

According to step (a) of the process of the present invention, a mineralfiller material is provided.

A mineral filler material in the meaning of the present invention refersto a substance of mineral origin which can be added to materials suchplastics to lower the consumption of more expensive materials such asbinders, or to enhance technical properties of the products. The personskilled in the art very well knows the typical fillers used in therespective fields. Mineral fillers as described herein may encompassnatural or synthetic minerals such as calcium carbonate, chalk,limestone, marble, dolomite, titanium dioxide, barium sulphate, talc,clay, or mica, and mixtures thereof, wherein the mineral filler materialpreferably is calcium carbonate and/or dolomite.

The mineral filler material according to the present invention may havea median particle size d₅₀ in the range from 0.001 μm to 100 μm,preferably from 0.5 to 5 μm.

According to one embodiment of the inventive process the mineral fillermaterial is selected from ground calcium carbonate, precipitated calciumcarbonate, surface modified calcium carbonate, dolomite, or mixturesthereof.

Ground calcium carbonate (GCC) in the meaning of the present inventionis a calcium carbonate obtained from natural sources which may beprocessed by, for example, grinding, screening and/or fractionizing bywet and/or dry, for example by a cyclone or classifier. Preferably, thenatural calcium carbonate is selected from the group consisting ofchalk, limestone, marble, or mixtures thereof.

Natural or ground calcium carbonate is known to exist as three types ofcrystal polymorphs: calcite, aragonite and vaterite. Calcite, the mostcommon crystal polymorph, is considered to be the most stable crystalform of calcium carbonate. Less common is aragonite, which has adiscrete or clustered needle orthorhombic crystal structure. Vaterite isthe rarest calcium carbonate polymorph and is generally unstable.

Precipitated calcium carbonate (PCC) in the meaning of the presentinvention is a synthesized material, generally obtained by precipitationfollowing a reaction of carbon dioxide and calcium hydroxide (hydratedlime) in an aqueous environment or by precipitation of a calcium- and acarbonate source in water. Additionally, precipitated calcium carbonatecan also be the product of introducing calcium and carbonate salts,calcium chloride and sodium carbonate for example, in an aqueousenvironment. PCC may be vaterite, calcite or aragonite.

Precipitated calcium carbonate (PCC) synthesis most commonly occurs by asynthetic precipitation reaction that includes a step of contactingcarbon dioxide with a solution of calcium hydroxide, the latter beingmost often provided on forming an aqueous suspension of calcium oxide,also known as burnt lime, and the suspension of which is commonly knownas milk of lime. Depending on the reaction conditions, this PCC canappear in various forms, including both stable and unstable polymorphs.Indeed, PCC often represents a thermodynamically unstable calciumcarbonate material. When referred to in the context of the presentinvention, PCC shall be understood to mean synthetic calcium carbonateproducts obtained by carbonation of a slurry of calcium hydroxide,commonly referred to in the art as a slurry of lime or milk of lime whenderived from finely divided calcium oxide particles in water. Preferredsynthetic calcium carbonate is precipitated calcium carbonate comprisingaragonitic, vateritic or calcitic mineralogical crystal forms ormixtures thereof.

Modified calcium carbonate (MCC) in the meaning of the present inventionmay feature a natural ground or precipitated calcium carbonate with aninternal structure modification or a surface-reaction product, i.e.surface-reacted calcium carbonate.

The term PCC likewise comprises PCC having a particle size in thenanometer range which is also referred to as ultrafine PCC or nano-PCC.More precisely, the term nano-PCC as used herein refers to PCC having aweight median particle size d₅₀ in the range from 1 to about 70 nm,whereas ultrafine PCC refers to PCC having a weight median particle sized₅₀ in the range from 70 to 1000 nm.

According to a preferred embodiment of the present invention the calciumcarbonate is a surface-treated or coated calcium carbonate, i.e. aground, precipitated or modified calcium carbonate comprising atreatment or coating e.g. with fatty acids, surfactants, siloxanes,polymers, or mixtures thereof.

According to another embodiment of the present invention the fillermaterial is ground dolomite.

Characterization of Step (b):

According to step (b) of the process of the present invention a polymermaterial is provided.

A polymer material as used in this application may comprisehomopolymers, copolymers such as, for example, block, graft, random andalternating copolymers, heterophasic copolymers and random heterophasiccopolymers as well as polymer blends, modifications, and mixturesthereof. The polymer material as used herein optionally may contain oneor more additives which are well known to the skilled person.

Such additives comprise, without being limited to, mineral fillers,fibres, lubricants, plasticizers, stabilizers (e. g. heat stabilizers orUV stabilizers), co-stabilizers, one packs, processing aids, impactmodifiers, flame retardants, antioxidants, biocides, blowing agents, andsmoke suppressors. Such additives can be present in amounts up to 100phr, preferably in an amount from 0.1 to 10 phr.

In the art and in particular in the field of polyvinyl chloride mixturescomprising stabilizers and lubricants are available, also referred to asone packs. Typical stabilizers may comprise lead stabilizers,calcium-zink stabilizers, organic based stabilizers, calcium organicbased stabilizers or tin stabilizers. Typical lubricants may compriseinternal lubricants such as fatty alcohols, dicarboxylic acid esters oroxidized polyethylene waxes, external lubricants such as paraffin wax orpolyethylene wax or lubricants with internal and external propertiessuch as ester wax or fatty acid esters.

The polymer material may be a neat or virgin polymer material or maycontain a mineral filler material which may be selected from theembodiments as defined above for step (a). However, any other suitablemineral filler material may be used.

According to one embodiment the mineral filler material present in thepolymer material provided in step (b) is identical to the mineral fillermineral material provided in step (a).

According to another embodiment the mineral filler material present inthe polymer material provided in step (b) is different from the mineralfiller material provided in step (a).

According to another embodiment the mineral filler material that ispresent in the polymer material provided in step (b) is different fromthe mineral filler which is already present in the polymer material asprovided in step (a).

According to one embodiment of the inventive process the polymermaterial provided in step (b) comprises a mineral filler material,wherein the content of the mineral filler material in the polymermaterial preferably is in the range from 1 to 70 phr, preferably from 5to 60 phr and more preferably from 10 to 50 phr.

The polymer material provided in step (b) may be produced in a hot-coldmixer according to which the mineral filler material and/or additives asdefined above may be added to a polymer material. In a first step of thehot-cold mixing a polymer material may be mixed with one or more of saidmineral filler material and/or additives in a hot-mixer until, forexample, a temperature of 120° C. is reached. In a second step, themixture then may be cooled, for example, to about 50° C. in acold-mixer.

According to another embodiment of the inventive process the polymermaterial may comprise recycled polymer material, wherein the recycledpolymer material preferably comprises a micronized recycled polymermaterial. The micronized recycled polymer material may have an averagegrain size in the range from 1 to 4000 μm. The content of recycledpolymer material in the polymer material may be in range from 0.1 to 100wt.-%.

According to another embodiment the polymer material comprises arecycled polyvinyl chloride (R-PVC) and preferably a micronized recycledpolyvinyl chloride.

According to yet another embodiment of the inventive process the polymermaterial comprises a polymer selected from the group consisting of vinylpolymers, vinyl copolymers, acryl polymers, acryl copolymers,chlorinated polyethylenes, and mixtures thereof, wherein the polymermaterial preferably comprises vinyl polymers and/or vinyl copolymers.For example, a vinyl polymer or vinyl copolymer may be a polyvinylchloride, a polyvinyl acetate, a polyvinyl alcohol, a polyvinylpyrrolidone, or a ethylene-vinyl acetate. An acryl polymer or acrylcopolymer, for example, may be a polyacryl acid, a polyacryl ester, apolyacrylonitrile, or a acrylic styrene acrylonitrile.

According to a preferred embodiment of the inventive process the polymermaterial comprises a polyvinyl chloride.

According to another embodiment of the inventive process the polymermaterial comprises suspension polyvinyl chloride (S-PVC), mass polyvinylchloride (M-PVC), or emulsion polyvinyl chloride (E-PVC).

According to another embodiment the k-value of the polymer material isin the range from 30 to 100, preferably from 45 to 70 and mostpreferably from 50 to 68, wherein the polymer material preferably is apolyvinyl chloride. The k-value is a measure of the molecular weight ofa polymer. For example, k-values of polyvinyl chloride may range from 30to 100. K-values of polyvinyl pyrrolidone may range from 10 to 120. Lowk-values imply low molecular weight (which is easy to process but hasinferior properties) and high k-values imply high molecular weight,(which is difficult to process, but has outstanding properties).

Characterization of Step (c):

According to step (c) of the process of the present invention themineral filler material of step (a) and the polymer material of step (b)are conveyed to a compounder.

The feeding of the mixture of the mineral filler material of step (a)and the polymer material of step (b) to the compounding section of thecompounder may be carried out by use of a conveying screw, preferably aco-rotating double screw, which may additionally be combined with astuffing device.

Characterization of Step (d):

According to step (d) of the process of the present invention acomposite polymer material is formed in the compounder, wherein themineral filler material of step (a) is added to the polymer material ofstep (b) in an amount so that the mineral filler content of theresulting composite polymer material is in the range from 60 to 900 phrand wherein said addition of the mineral filler material to the polymermaterial is performed by use of direct addition technology.

The compounder used according to the inventive process can be any devicewhich is suitable for compounding the polymer material with the mineralfiller. Such devices are known in the art.

According to one embodiment, the compounder is an extruder or aco-kneader, e.g. a twin screw extruder, a Buss co-kneader, or a Farrelmixer. In the extruder or co-kneader the polymer material may becompounded with the mineral filler in an at least partially moltenstate, i.e. at temperatures above 20° C. Optionally, the extruder can beequipped with a stuffing device.

According to one preferred embodiment, the compounder is an extruder,wherein the temperature of the polymer melt preferably is kept below205° C., preferably between 160 and 200° C. This is particularlyimportant if the polymer material comprises a polyvinyl chloride.

The term “direct addition technology” as used herein comprises theaddition and mixing of a mineral filler material to a polymer materialin a direct addition device upstream from a compounding section of acompounder, wherein the direct addition device is in direct connectionto the compounding section of the compounder and preferably above saidcompounding section of the compounder, so that no pneumatic conveying ofthe resulting mixture to the compounding section is involved.Optionally, feeding of the resulting mixture to the compounding sectionof the compounder may be carried out by use of a conveying screw,preferably a co-rotating double screw, which may additionally becombined with a stuffing device. The compounding section is a part ofthe compounder, in which the mineral filler material and the polymermaterial are actually compounded. If the compounder is a screw extruder,for example, the compounding section would be the screw cylinderincluding the extruder screw(s) wherein the mineral filler material andthe polymer material are compounded.

The addition of the mineral filler material to the polymer materialupstream from the compounding section may be carried out using at leastone metering unit. According to one embodiment, the mineral fillermaterial is added by the use of a metering unit, preferably a volumetricmetering unit, or a gravimetric metering unit.

The compounder may be any device which is suitable for compounding oneor more polymer material with one or more additives including themineral filler material. Said compounder comprises a compoundingsection, in which the mineral filler material and the polymer materialare actually compounded. Such devices are known in the art. A mixingdevice for direct addition technology can be connected to thecompounder, preferably located upstream from the compounding section ofthe compounder, wherein the mixing device preferably is a mixer and morepreferably is a cold-mixer. Suitable mixing devices are known to theskilled person.

According to one embodiment the mineral filler is added to the polymermaterial in an amount so that the mineral filler content of theresulting composite polymer material is in the range from 150 to 800phr, preferably in the range from 160 to 700 phr, and more preferably inthe range from 170 to 600 phr.

According to another preferred embodiment the mineral filler content ofthe resulting composite polymer material is in the range from 150 to 800phr, in the range from 200 to 700 phr, in the range from 250 to 700 phr,in the range from 250 to 600 phr, in the range from 350 to 600 phr or inthe range from 400 to 500 phr.

Optionally, further additives known to the skilled person may be addedduring process step (d). Such additives comprise, without being limitedto, mineral fillers, fibres, lubricants, plasticizers, stabilizers (e.g. heat stabilizers or UV stabilizers), co-stabilizers, one packs,processing aids, impact modifiers, flame retardants, antioxidants,biocides, blowing agents, and smoke suppressors. Such additives can bepresent in amounts up to 100 phr, preferably in an amount from 0.1 to 10phr.

According to one embodiment, in process step (d) the composite polymermaterial is formed into a granulate having an average grain size rangingfrom 2 to 8 mm, preferably from 3 to 7 mm, and more preferably from 4 to6 mm.

Granulation may be carried out with the compounder used in step (d) ofthe inventive process. For example, the composite polymer material isformed into a granulate by pressing the compounded mineral fillermaterial and polymer material through a die equipped with a cuttingknife, wherein the granule size may be regulated by the applied pressureand/or the cutting speed. However, any other system that is suitable toproduce granulates may be used.

According to one embodiment, the composite polymer material obtained bythe process steps (a) to (d) of the inventive process is micronized toyield an average grain size of less than 4 mm, preferably less than 3mm, and most preferably less than 2 mm.

According to another especially preferred embodiment of the presentinvention, a composite polymer material is formed, wherein a mineralfiller material is added to a polymer material in an amount so that themineral filler content of the resulting composite polymer material is inthe range from 60 to 900 phr, wherein said addition of the mineralfiller material to the polymer material is performed by use of directaddition technology and wherein the obtained composite polymer materialis micronized to yield an average grain size of less than 4 mm,preferably less than 3 mm and most preferably less than 2 mm.

According to yet another especially preferred embodiment of the presentinvention, a composite polymer material is formed, wherein a mineralfiller material is added to a polymer material in an amount so that themineral filler content of the resulting composite polymer material is inthe range from 60 to 900 phr, wherein said addition and mixing of themineral filler material to the polymer material is performed in a directaddition device upstream from the compounding section of the compounder,wherein the direct addition device is in direct connection to thecompounding section of the compounder and preferably above saidcompounding section of the compounder, so that no pneumatic conveying ofthe resulting mixture to the compounding section is involved and whereinthe obtained composite polymer material is micronized to yield anaverage grain size of less than 4 mm, preferably less than 3 mm and mostpreferably less than 2 mm.

The composite polymer material may be micronized by methods known in artfor the reduction of the average grain size. Such methods include,without being limited to, milling, bashing and grinding as well asmethods involving supercritical fluids.

The Composite Polymer Material

According to one aspect of the present invention, a composite polymermaterial obtainable by the inventive process is provided. Said compositepolymer material may have a defined shape, such as pellets, spheres,pearls, beads, prills, flakes, chips or slugs, a non-defined shape suchas, for example, crumbles or it may be a mixture of both defined andnon-defined shape composite polymer materials.

According to a further aspect of the present invention, a compositepolymer material is provided in the form of grains having an averagegrain size of less than 4 mm, preferably less than 3 mm and mostpreferably less than 2 mm.

The inventors surprisingly found that the inventive composite polymermaterial has several advantageous properties:

The inventive process allows the replacement of polymer material by themineral filler material. This can lead to a cost reduction in themanufacturing of polymer products.

Furthermore, the increased filler contents may lead to a compositepolymer material having a high E-modulus, which in turn may allowreducing the wall thickness of polymer products. Due to an increasedhigher thermal conductivity of the inventive composite polymer material,cooling time in the provision of polymer products may also be reduced.

By means of the inventive process formation of filler material depositsin the hot-cold mixer as well as segregation problems when pneumaticallyconveying the dry-blend obtained from the hot-cold mixing to thecompounder may be avoided.

Furthermore, the inventive composite polymer material allows adaptingthe filler content of a polymer product to a predetermined value andmoreover allows precise and uniform dosage.

Due to an increased higher thermal conductivity of the inventivecomposite polymer material cooling time in the provision of polymerproducts may be reduced.

Moreover problems in connection with dust formation may be avoided whenusing the composite polymer material as masterbatch for increasing thefiller content in polymer products.

According to another embodiment the composite polymer materialobtainable according to the inventive process may be used in polymerproducts. According to a preferred embodiment, the inventive compositepolymer material is used in polymer products as a masterbatch.

According to another embodiment a polymer product comprising theinventive composite polymer material is provided.

According to yet another embodiment the polymer product may be agranulate, window profile, pipe, technical profile, wall panel, ceilingpanel, cladding panel, wire or cable insulation, film, sheet, fibre, ora non-woven. Such polymer products can be produced by processescomprising an extrusion step, injection moulding, blow moulding, orcasting.

EXAMPLES

The scope and interest of the invention may be better understood basedon the following examples which are intended to illustrate certainembodiments of the present invention and are non-limitative.

Measurements

K-Value

A measure of the molecular weight of a polymer based on measurements ofviscosity of a polymer solution and is defined as follows:

$\frac{\log \left( {N_{S}/N_{0}} \right)}{c} = {\frac{75\; K^{2}}{1 + {1.5\; {Kc}}} + K}$

In general, k-values for a particular polymer may be requested from thepolymer producer or may be taken on the packaging or the accompanyingtechnical data sheet.

Particle Size of the Mineral Filler Material

The particle size distribution of the filler material may be measuredusing a Sedigraph 5120 from the company Micromeritics, USA. The methodand the instruments are known to the skilled person and are commonlyused to determine grain size of fillers and pigments. The measurementmay be carried out in an aqueous solution comprising 0.1 wt.-% Na₄P₂O₇.The samples were dispersed using a high speed stirrer and supersonics.

Average Grain Size of the Composite Polymer Material

The average grain size of the composite polymer material is the weightmedian grain size, i.e. 50 wt.-% of all grains are bigger or smallerthan this average grain size. The grain size is determined by sievingaccording to ISO 3310-1:2000 (E).

General Procedure

Amounts and specifications of components used herein can be taken fromthe table given for examples 1-4.

The corresponding polymer material may be provided in a hot-mixer.Stabilizer (S), lubricant (L), optional plasticizer (P), optionalco-stabilizer (C), an optional processing additive (A) and/or calciumcarbonate (F1) may be added and mixed until a temperature of about 120°C. is reached. The mixture then may be cooled down to about 50° C. in acold-mixer. The mixture may be conveyed to a compounder. By use ofdirect addition technology further calcium carbonate (F2) as mineralfiller material may be added and the resulting mixture may be fed intothe compounding section of an extruder, preferably by use of aco-rotating double screw combined with a stuffing device. Optionally,the obtained granulate may be micronized e.g. by using a Pallmann millto yield an average grain size of less than 2 mm.

Materials

Polymer Material: Polyvinyl Chloride (PVC)

Vestolit® P 1982 K, commercially available from Vestolit GmbH & Co. KG,Germany, k=65.

Polymer Material: Polyvinyl Chloride (PVC)

Vinnolit® E 2059, commercially available from Vinnolit GmbH & Co. KG,Germany, k=59.

Polymer Material: Polyvinyl Chloride (PVC)

INEOS S 5730 Suspenion PVC, commercially available from INEOS VinylsDeutschland GmbH, Germany, k=57.

Polymer Material: Micronized Recycled Polyvinyl Chloride (R-PVC)

Commercially available from Tonsmeier Kunststoffe, Germany. Averagegrain size: 0.5 to 1.0 mm.

Co-Stabilizer: Epoxidized Soybean Oil (ESBO)

Viko ex 7170, commercially available from ARKEMA, France.

Plasticizer: 1,2-Cyclohexane Dicarboxylic Acid Diisononyl Ester (DINCH)

Hexamoll® DINCH®, commercially available from BASF SE, Germany.

Filler Material: Hydrocarb 95T-OG

Ground calcium carbonate, commercially available from Omya AG,Switzerland. Particle size d₅₀: 0.8 μm; top cut d₉₈: 5.0 μm.

Filler Material: Omyalite 50H-OM

Ground calcium carbonate, commercially available from Omya AG,Switzerland. Particle size d₅₀: 2.0 μm; top cut d₉₈: 10 μm.

Filler Material: Omya BSH®-OM

Ground calcium carbonate, commercially available from Omya AG,Switzerland. Particle size d₅₀: 2.4 μm; top cut d₉₈: 20 μm.

In the art and in particular in the field of polyvinyl chloride (PVC)processing mixtures comprising stabilizers and lubricants are available,also referred to as one packs. Typical stabilizers may comprise leadstabilizers, calcium-zink stabilizers, organic based stabilizers,calcium organic based stabilizers or tin stabilizers. Typical lubricantsmay comprise internal lubricants such as fatty alcohols, dicarboxylicacid esters or oxidized polyethylene waxes, external lubricants such asparaffin wax or polyethylene wax or lubricants with internal andexternal properties such as ester wax or fatty acid esters.

For example, a preferred one pack comprises:

 3.5 phr calcium-zink stabilizer,  0.3 phr polyethylene wax, 0.25 phrparaffin wax, and  0.2 phr oxidized polyethylene wax.

Examples 1-4

The following illustrative examples may be prepared according to thegeneral procedure given above.

1 2 3 4 polymer Vestolit ® Vinnolit ® INEOS R-PVC material P 1982 K E2059 S 5730 (micronized) S, L One Pack One Pack One Pack One Pack (3phr) (4 phr) (5 phr) (2 phr) P — — Hexamoll ® — DINCH ® (4 phr) C —Vikoflex ® — — 7170 (2 phr) F1 Hydrocarb ® — Omyalite ® — 95T-OG 50H-OM(20 phr) (10 phr) F2 Hydrocarb ® Omyalite ® Omyalite ® Omya 95T-OG90T-OM 50H-OM BSH ®-OM (170 phr) (200 phr) (300 phr) (400 phr) F1 + 190phr 200 phr 310 phr 400 phr F2

Examples 5-8

S-PVC (INEOS S 5730, k=57) was dry blended with calcium carbonate(Omyalite® 50H-OM), stabilizer (BAEROPAN R 91800 P/1-CC) andco-stabilizer (ESBO). The blend was charged into a Coperion ZSK 26/60 MCextruder, wherein additional calcium carbonate (Omyalite® 50H-OM) wasadded by direct addition using an extra metering unit. Redispersionquality of the extrusion product was controlled via profile extrusionand visual inspection. The results of the different trials are listed inthe table below.

5 6 7 8 dry INEOS INEOS INEOS INEOS blend S 5730 S 5730 S 5730 S 5730Omyalite ® Omyalite ® Omyalite ® Omyalite ® 50H-OM 50H-OM 50H-OM 50H-OM(30 phr) (30 phr) (30 phr) (30 phr) BAEROPAN BAEROPAN BAEROPAN BAEROPAN(3.4 phr) (3.4 phr) (3.4 phr) (3.4 phr) — ESBO ESBO ESBO (0 phr) (0 phr)(0 phr) extrude 46.7 kg/h 48.7 kg/h 49.5 kg/h 54.5 kg/h output CaCO₃ via 4.5 kg/h  3.5 kg/h  2.7 kg/h  2.4 kg/h d blend (clcd. CaCO₃ via 26.5kg/h 29.5 kg/h 34.5 kg/h 41.5 kg/h direct addition total 31.0 kg/h 33.0kg/h 37.2 kg/h 43.9 kg/h CaCO₃ filler content of 66.4 wt.-% 67.8 wt.-%75.1 wt.-% 88.7 wt.-% the composite dispersion excellent excellent goodacceptable, quality some small agglomerates

1. A process for the production of a composite polymer material, whereinthe process comprises the steps of: (a) providing a mineral fillermaterial; (b) providing a polymer material; (c) conveying the mineralfiller material of step (a) and the polymer material of step (b) to acompounder; (d) forming a composite polymer material in said compounder;wherein the mineral filler material of step (a) is added to the polymermaterial of step (b) in an amount so that the mineral filler content ofthe resulting composite polymer material is in the range from 60 to 900phr and wherein the mineral filler material of step (a) is added to thepolymer material of step (b) by use of direct addition technology, saidtechnology comprising the addition and mixing of said mineral fillermaterial to said polymer material in a direct addition device in directconnection to the compounding section of the compounder so that nopneumatic conveying of the resulting mixture to the compounding sectionis involved and wherein said compounder is an extruder.
 2. The processaccording to claim 1, characterized in that the mineral filler contentof the resulting composite polymer material is in the range from 150 to800 phr.
 3. The process according to claim 1, characterized in that thecomposite polymer material in step (d) is produced in form of agranulate having an average grain size ranging from 2 to 8 mm.
 4. Theprocess according to claim 1, characterized in that the obtainedcomposite polymer material is micronized to yield an average grain sizeof less than 4 mm.
 5. The process according to claim 1, characterized inthat the polymer material provided in step (b) comprises a mineralfiller material.
 6. The process according to claim 1, characterized inthat the polymer material provided in step (b) comprises a recycledpolymer material.
 7. The process according to claim 1, characterized inthat the temperature of the polymer melt preferably is kept below 205°C.
 8. The process according to claim 1, characterized in that themineral filler material is selected from the group consisting of calciumcarbonate, chalk, limestone, marble, dolomite, titanium dioxide, bariumsulphate, talc, clay, or mica, and mixtures thereof, wherein the mineralfiller material preferably is calcium carbonate and/or dolomite.
 9. Theprocess according to claim 1, characterized in that the mineral fillermaterial is selected from ground dolomite, ground calcium carbonate(GCC), precipitated calcium carbonate (PCC), modified calcium carbonate(MCC), or mixtures thereof.
 10. The process according to claim 1,characterized in that the polymer material comprises a polymer selectedfrom the group consisting of vinyl polymers, vinyl copolymers, acrylpolymers, acryl copolymers, chlorinated polyethylenes, and mixturesthereof.
 11. A composite polymer material obtainable by a processaccording to claim
 1. 12. A composite polymer material comprising amineral filler material and a polymer material, wherein the compositepolymer material is in the form of grains having an average grain sizeof less than 4 mm and wherein the filler content in the compositepolymer material is in the range from 60 to 900 phr.
 13. The compositepolymer material according to claim 12, characterized in that themineral filler content of the composite polymer material is in the rangefrom 150 to 800 phr.
 14. A polymer product comprising the compositepolymer material of claim
 1. 15. A masterbatch or polymer productcomprising Use of the composite polymer material according to claim 11.